Raised expression of APRIL in Chinese children with acute lymphoblastic leukemia and its clinical implications

This study was to determine the expression of a proliferation-inducing ligand (APRIL) and its receptors, B-cell maturation antigen (BCMA) and transmembrane activator and calcium-modulating cyclophilin ligand interactor in childhood acute lymphoblastic leukemia (ALL). The correlation between the plasma APRIL levels and clinical status was also evaluated. Plasma samples from 20 untreated children with ALL, 23 children with ALL in remission, and 15 normal controls were assayed for APRIL plasma concentration by enzyme-linked immunosorbent assay. Real-time quantitative polymerase chain reaction was performed to determine the mRNA expression of APRIL and its receptors in blood mononuclear cells in 20 untreated ALL children and 15 normal controls. The untreated ALL patients had higher plasma APRIL levels than the remission group and the normal controls (P<0.001, respectively). No significant difference was found between the remission group and the normal controls in the plasma APRIL levels (P=0.339). The plasma APRIL levels in the untreated patients correlated with white blood cell count at diagnosis (P=0.002) and risk category (P=0.013). The mRNA expression of both APRIL and BCMA in blood mononuclear cells of the ALL patients were higher than those of the normal controls (both P<0.001). No significant difference was found between the patients and the normal controls in the transmembrane activator and calcium-modulating cyclophilin ligand interactor expression (P>0.05). These findings indicate that APRIL and BCMA are over expressed in untreated ALL children. The levels of APRIL correlate with the progression of childhood ALL, which may provide certain clues for monitoring ALL clinically.